It has also emerged that another key aide, Unite official Andrew Murray, has been working without required security clearance.

The House of Commons has launched an investigation into claims that Jeremy Corbyn’s office broke strict rules on Parliamentary security.

The move was announced after HuffPost UK revealed on Tuesday that a close aide of the Labour leader had been working in the Palace of Westminster without required security clearance.

Iram Awan, Corbyn’s Private Secretary, has routinely turned up for work at his Commons office for more than nine months despite failing to gain a Parliamentary pass.

Awan has used a visitor’s pass to gain access and has been escorted by Labour staff to Corbyn’s office on a regular basis.

A Commons spokesman said: “Visitor passes are for visitors only; they cannot be used to carry out work on the parliamentary estate.

“An investigation into an alleged breach of Parliamentary rules has been launched and so we will not be commenting further.”

A spokesman for Corbyn said: “We don’t comment on staffing matters”.

But a Labour source said: “We have not been told that any member of staff has been refused a pass or any reasons for why any pass may not have yet been granted.”

It is understood that Corbyn’s office on Wednesday raised delays in pass approvals with the Commons authorities.

Awan is expected to spend more time working outside Parliament, but will still attend meetings with the Labour leader

The FT reported on Wednesday that another key aide to Corbyn, Unite official Andrew Murray, has been working on an occasional basis in the Labour leader’s office without required security clearance.

Murray, a former Communist party member and longstanding ally of Corbyn, is understood to have been given a Parliamentary Lobby pass when he worked for the Morning Star newspaper in the 1980s.

Yet is still waiting for his own security pass to be approved a year after first applying for one, HuffPost UK has been told.

Murray, who works on secondment for the leader, applied last October for a pass. He has not been told his pass has been rejected or given any reason.

The delay has infuriated Murray. Someone close to him told HuffPost: “Andrew considers this a petty attempt to disrupt the working of the Leader’s office.”

The announcement of an investigation came after Tory MP Leo Doherty wrote to the Serjeant at Arms, Kamal El-Hajji – the Commons’ senior security official – to request an investigation.

“Whilst applicants for a Parliamentary pass will normally go through the Counter-Terrorist Check (CTC), it appears in this case that due to unspecified concerns raised by the security services,” Doherty wrote.

“Awan has not received the necessary clearance. It is further concerning that reports have stated Mr Corybn knew his employee did not have the necessary clearance, and that she continued to work in his office on the estate.

“You will not need me to remind you how we have seen in recent months and years how the security of Parliament is a matter of the utmost importance.

“It is incumbent upon all of us who work on the Parliamentary estate, whatever role it is in or party we represent, to ensure the proper procedure is followed always.

“I would therefore request you investigate this matter with urgency it deserves, so we can all be sure that security around the Parliamentary estate is as strong as it can be.”